Flexible snares introduced by endoscopes are widely used in surgical procedures requiring the removal of selected body tissue or of an organ from inside of a body cavity. The snare, typically a loop or noose formed at the distal end of a flexible metal wire, is moved from the distal end of the endoscope or laparoscope!* by movement of a handle or plunger attached to its proximal end. The snare can be used in conjunction with cautery in order to cauterize the tissue at the site of the resection and thereby reduce or eliminate bleeding.
However, depending on the size, condition and nature of the tissue or the organ that is to be resected by the snare, complications in the form of excessive bleeding at the site can occur. For example, during a fiberoptic colonoscopy, a polyp is visualized by the endoscopist and the loop of the metal cautery snare is placed around the stalk of the polyp. The proximal end of the snare is attached to an electrical power source. The snare is tightened upon the stalk of the polyp, the cautery is applied and the polyp is transected.
Polyps are pre-malignant lesions which, if left in the colon, become cancerous. There are about 600,000 polypectomies performed each year in the United States alone. Of these, approximately 200,000 procedures involve large polyps. Large polyps are those measuring 2 cm or more in diameter. A polyp of this size is carried by a stalk that has an artery running through it. The artery supplies the polyp with blood, and when the stalk is transected by the snare, there is a danger that this artery will bleed. The larger the polyp, the larger is the blood supplying artery in the stalk and the greater the danger of bleeding.
When such arterial bleeding occurs, the lumen of the colon fills with blood, and it is extremely difficult for the surgeon to see the stalk from which the blood is spouting. If the stalk can be visualized, the endoscopist tries to re-snare the transected stalk, tighten the snare upon it and, if successful, must then hold the snare in this position for 15 minutes hoping for coagulation to occur and for the bleeding to stop. If the bleeding does not stop, or if the stalk cannot be re-snared, the patient has to have immediate surgery, and the segment of colon with the bleeding artery has to be resected.